Moldable polyester compositions, processes of manufacture, and articles thereof

ABSTRACT

A thermoplastic composition comprises, based on the total weight of the composition: 51-90 wt % of a polyester, 10-49 wt % of an ABS impact modifier; 0 to 20 wt % of a multifunctional epoxy compound; 0-40 wt % of a filler; 0-2 wt % of a fibrillated fluoropolymer; and from more than 0 to 5 wt % of a stabilizer composition. An article blow molded or injection molded from the composition has a multi-axial impact total energy from 40-100 Joules at −30° C.; a ductility of more than 90%, a permeability of more than 0 to less than or equal to 1.5 g/m 2 -day, measured after exposure Fuel C vapor for 20 weeks at 40° C.; an MVR of 1-20 cc/10 min; a flexural modulus of greater than 1300 MPa; and retains at least 75% of its initial tensile elongation at break after exposure to Fuel E85 for 28 days at 70° C.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 61/021,269, filed on Jan. 15, 2008, which in incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

This disclosure relates to polyester compositions, processes ofmanufacture, and articles thereof.

Polyesters, copolyesters, and their blends with other thermoplasticshave a number of advantageous properties, in particular high mechanicalstrength and good processability, which make them useful in a widevariety of applications. Nonetheless, there remains a long felt need formethods for improving specific property combinations in polyestercompositions, compositions (and articles made from the compositions)that exhibit a certain combination of useful properties, regardlesswhether the composition is subjected to an injection molding process ora blow molding processes. One such combination is good low temperatureductility, low permeability, and chemical resistance. A combination oflow temperature ductility, low permeability, and good chemicalresistance would be useful for articles that are manufactured byinjection or blow molding processes. These features are especiallyuseful for fuel tanks, such as gasoline containers, which must remain incontact with fuels for extended periods. These tanks are oftenmanufactured by blow molding.

Unfortunately, ordinary technology and available information has beenunable in disclosing or teaching polyester compositions that exhibit acombination of low temperature ductility and good chemical resistanceand low permeability that are manufactured by injection or blow moldingprocesses. Blow-molding processes are typically more demanding processthan injection molding processes, because, in part, the conditionscreated by blow molding processes subject the molten polymer to air forrelatively longer periods of time than injection moldingprocesses-factors that have been known to adversely affect theproperties of the compositions and the articles made from them.Improvements in low temperature ductility, for instance by addition ofrubbery impact modifier or ductile polymer such as polycarbonate havebeen found to degrade the chemical resistance and low permeability ofpolyester compositions, and conversely, improvements in chemicalresistance, particularly to fuels and/or short chain alcohols, have beenfound to worsen low temperature ductility. Further, regulatory changeshave created the need for improved polymers that exhibit a usefulcombination of low temperature ductility, good chemical resistance, andlow permeability when exposed to gasoline, biofuels such asethanol-containing fuels, and other new fuels.

For the foregoing reasons, there remains a need in the art for polyestercompositions that have improved low temperature ductility and goodchemical resistance, particularly when articles formed from thecompositions are blow molded.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, the invention relates to a thermoplastic compositioncomprising, based on the total weight of the composition:

from 51 to 90 wt % of a polyester having

-   -   a weight average molecular weight from 20,000 to 80,000 daltons,    -   a carboxylic acid end group content from 5 to 50 meq/Kg, and    -   a melting point temperature from 200 to 285° C.,    -   wherein the polyester is selected from the group consisting of        poly(ethylene terephthalate)s, poly(1,4-butylene        terephthalate)s, poly(1,3-propylene terephthalate)s,        poly(cyclohexanedimethanol terephthalate)s,        poly(cyclohexanedimethylene terephthalate)-co-poly(ethylene        terephthalate)s, and a combination thereof;

from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impact modifiercomposition, having

-   -   an average particle size of 50 to 400 micrometers,    -   a gel content of at least 50 wt %,    -   a polybutadiene content of at least 50 wt % of the impact        modifier composition, and    -   a soluble styrene-acrylonitrile copolymer content ranging from 0        to 5 wt % of the impact modifier composition;

from 0 to 20 wt % of a multifunctional epoxy compound;

from 0 to 40 wt % of a filler;

from 0 to 2 wt % of a fibrillated fluoropolymer; and

from more than 0 to 5 wt % of a stabilizer composition comprising astabilizer selected from the group consisting of thioether esters,hindered phenols, phosphites, phosphonites, phosphoric acid, and acombination thereof, wherein at least one of the foregoing stabilizershas a molecular weight of greater than 500 daltons;

wherein an article that is blow molded or injection molded from thethermoplastic composition

-   -   has a multi-axial impact total energy ranging from 40 to 100        Joules at −30° C., measured in accordance with ASTM D3763, and a        ductility of more than 90%    -   has a permeability of more than 0 and less than or equal to 1.5        g/m²-day to ASTM D 471-98 Fuel C, measured after exposure to        ASTM D 471-98 Fuel C vapor for 20 weeks at 40° C., using a disc        having a diameter of 22 mm and a thickness of 2 mm;    -   has an MVR of 1 to 20 cc/10 min., measured in accordance with        ASTM D1238 at 265° C.;    -   has a flexural modulus of greater than 1300 MPa, measured in        accordance with ASTM D790; and    -   retains at least 75% of its initial tensile elongation at break,        as measured by ASTM D638, after exposure to Fuel E85 for 28 days        hours at 70° C.

In another embodiment, the invention relates to a thermoplasticcomposition comprising, based on the total weight of the composition:

from 51 to 90 wt % of a polyester having

-   -   a weight average molecular weight from 20,000 to 80,000 daltons,    -   a carboxylic acid end group content from 5 to 50 meq/Kg, and    -   a melting point temperature from 200 to 285° C.,    -   wherein the polyester is poly(1,4-butylene terephthalate)s,    -   from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impact        modifier composition, having    -   an average particle size of 50 to 400 micrometers,    -   a gel content of at least 50 wt %,    -   a polybutadiene content of at least 50 wt % of the impact        modifier composition, and    -   a soluble styrene-acrylonitrile copolymer content ranging from 0        to 5 wt % of the impact modifier composition;

from more than 0 to 20 wt % of a multifunctional epoxy compound;

from 0 to 40 wt % of a filler;

from 0.1 to 1.0 wt. % of a fibrillated fluoropolymer, the fibrillatedfluoropolymer being an encapsulated fluoropolymer comprisingpoly(tetrafluoroethylene) encapsulated with styrene-acrylonitrile;

from more than 0 to 5 wt % of a stabilizer composition comprising astabilizer selected from the group consisting of thioether esters,hindered phenols, phosphites, phosphonites, phosphoric acid, and acombination thereof, wherein at least one of the foregoing stabilizershas a molecular weight of greater than 500 daltons;

wherein an article that is blow molded or injection molded from thethermoplastic composition

-   -   has a multi-axial impact total energy ranging from 40 to 100        Joules at −30° C., measured in accordance with ASTM D3763, and a        ductility of more than 90%;    -   has a permeability of more than 0 and less than or equal to 1.5        g/m²-day to ASTM D 471-98 Fuel C, measured after exposure to        ASTM D 471-98 Fuel C vapor for 20 weeks at 40° C., using a disc        having a diameter of 22 mm and a thickness of 2 mm;    -   has an MVR of 1 to 20 cc/10 min, measured in accordance with        ASTM D1238 at 265° C.;    -   has a flexural modulus of greater than 1300 MPa, measured in        accordance with ASTM D790; and    -   retains at least 75% of its initial tensile elongation at break,        as measured by ASTM D638, after exposure to Fuel E85 for 28 days        at 70° C.

In another embodiment, an injection molded article comprises thethermoplastic composition.

In another embodiment, a blow molded article comprises the thermoplasticcomposition.

In another embodiment, the invention relates to a process for blowmolding a fuel tank, which comprises:

heating a thermoplastic composition in a screw-driven melt processingdevice to a temperature of 230 to 300° C. to form a molten composition;

pushing the molten composition through an orifice to create an annulartube of the molten thermoplastic composition;

closing off an end of the annular tube to form a closed end annulartube;

encasing the closed ended annular tube in a mold;

blowing a gas into the closed ended annular tube while the thermoplasticcomposition is above the crystallization temperature of the composition,until the closed ended tube assumes the shape of the mold to form ashaped tube; and

cooling the shaped tube to temperature below the crystallizationtemperature of the thermoplastic composition to form the article;

wherein the composition comprises

from 51 to 90 wt % of a polyester having

-   -   a weight average molecular weight from 20,000 to 80,000 daltons,    -   a carboxylic acid end group content from 5 to 50 meq/Kg, and    -   a melting point temperature from 200 to 285° C.,    -   wherein the polyesters is selected from the group consisting of        poly(ethylene terephthalate)s, poly(1,4-butylene        terephthalate)s, poly(1,3-propylene terephthalate)s,        poly(cyclohexanedimethanol terephthalate)s,        poly(cyclohexanedimethylene terephthalate)-co-poly(ethylene        terephthalate)s, and a combination thereof;

from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impact modifiercomposition, having

-   -   an average particle size from 50 to 400 micrometers,    -   a gel content of at least 50 wt %, and    -   a polybutadiene content of at least 50 wt % of the impact        modifier composition;

from 0 to 20 wt % of a multifunctional epoxy compound;

from 0 to 40 wt % of a filler;

from 0 to 2 wt % of a fibrillated fluoropolymer; and

from more than 0 to 5 wt % of a stabilizer composition, wherein thestabilizer composition comprises at least 20 wt % of the thioetherester, based on the weight of the stabilizer composition, and at leastone additional stabilizer selected from the group consisting of hinderedphenols, phosphites, phosphonites, phosphoric acid, and a combinationthereof;

wherein each of the foregoing stabilizers has a molecular weight ofgreater than 500 daltons; and

wherein a blow molded sample of the composition has a multi-axial impacttotal energy from 40 to 100 Joules at −30° C., measured in accordancewith ASTM D3763.

Various other features, aspects, and advantages of the present inventionwill become more apparent with reference to the following description,examples, and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on the unexpected discovery that polyestercompositions with improved low temperature ductility and good chemicalresistance and permeability can be obtained using specific combinationof certain high molecular weight polyesters, specific impact modifiershaving particular properties, and a stabilizer composition. Thecomposition can further include a multifunctional epoxy compound and/ora fluoropolymer when specific performance properties are needed. Inparticular, the compositions have good ductility, low permeability, andresistance to gasoline and short chain alcohols. These properties areespecially useful for the manufacture of articles such as fuel tanks andcontainers for gasoline. Such properties are advantageously alsoobtained when the compositions are blow molded or injection molded toform articles.

The singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. The terms “first,” “second,” andthe like herein do not denote any order, quantity, or importance, butrather are used to distinguish one element from another. As used herein,the “(meth)acryl” prefix includes both the methacryl and acryl. Unlessdefined otherwise, technical and scientific terms used herein have thesame meaning as is commonly understood by one of skill. Compounds aredescribed using standard nomenclature.

Other than in the operating examples or where otherwise indicated, allnumbers or expressions referring to quantities of ingredients, reactionconditions, and the like, used in the specification and claims are to beunderstood as modified in all instances by the term “about.” Variousnumerical ranges are disclosed in this patent application. Because theseranges are continuous, they include every value between the minimum andmaximum values. Unless expressly indicated otherwise, the variousnumerical ranges specified in this application are approximations. Theendpoints of all ranges directed to the same component or property areinclusive of the endpoint and independently combinable.

All ASTM tests and data are from the 2003 edition of the Annual Book ofASTM Standards unless otherwise indicated.

The thermoplastic compositions disclosed herein comprise based on thetotal weight of the composition: from 51 to 90 wt % of a polyester, 10to 49 wt % of an acrylonitrile-butadiene-styrene impact modifier, from 0to 20 wt % of a multifunctional epoxy compound; from 0 to 40 wt % of afiller; from 0 to 2 wt % of a fibrillated fluoropolymer; and from morethan 0 to 5 wt % of a stabilizer. An article which is blow molded orinjection molded from the thermoplastic composition has a ductility ofmore than 90% and a multi-axial impact total energy ranging from 40 to100 Joules at −30° C., measured in accordance with ASTM D3763. Thearticle also has a permeability of more than 0 and less than or equal to1.5 g/m²-day to ASTM D 471-98 Fuel C, measured after exposure to ASTM D471-98 Fuel C vapor for 20 weeks at 40° C., using a disc having adiameter of 22 mm and a thickness of 2 mm. The article also has an MVR(melt volume flow rate) of 1 to 20 cc/10 min., measured in accordancewith ASTM D1238 at 265° C. The article also has a flexural modulus ofgreater than 1300 MPa, measured in accordance with ASTM D790. Thearticle also retains at least 75% of its initial tensile elongation atbreak, as measured by ASTM D638, after exposure to Fuel E85 for 28 daysat 70° C.

Polyesters for use in the present thermoplastic compositions havingrepeating structural units of formula (1)

wherein each T is independently the same or different divalent C₆₋₁₀aromatic group derived from a dicarboxylic acid or a chemical equivalentthereof, and each D is independently a divalent C₂₋₄ alkylene groupderived from a dihydroxy compound or a chemical equivalent thereof.Copolyesters containing a combination of different T and/or D groups canbe used. Chemical equivalents of diacids include the correspondingesters, alkyl esters, e.g., C₁₋₃ dialkyl esters, diaryl esters,anhydrides, salts, acid chlorides, acid bromides, and the like. Chemicalequivalents of dihydroxy compounds include the corresponding esters,such as C₁₋₃ dialkyl esters, diaryl esters, and the like. The polyesterscan be branched or linear.

Examples of C₆₋₁₄ aromatic dicarboxylic acids that can be used toprepare the polyesters include isophthalic acid, terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid, and the like, and 1,4- or 1,5-naphthalenedicarboxylic acids and the like. A combination of isophthalic acid andterephthalic acid can be used, wherein the weight ratio of isophthalicacid to terephthalic acid is 91:9 to 2:98, specifically 25:75 to 2:98.

Exemplary diols useful in the preparation of the polyesters include C₂₋₄aliphatic diols such as ethylene glycol, 1,2-propylene glycol,1,3-propylene glycol, 1,4-butane diol, 1,2-butylene diol, 1,4-but-2-enediol, and the like. In one embodiment, the diol is ethylene and/or1,4-butylene diol. In another embodiment, the diol is 1,4-butylene diol.In still another embodiment, the diol is cyclohexanedimethanol.

Specific exemplary polyesters include poly(ethylene terephthalate)(PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylenenaphthalate) (PEN), poly(butylene naphthalate) (PBN), andpoly(1,3-propylene terephthalate) (PPT). In one embodiment, thepolyester is PET and/or PBT. In still another specific embodiment, thepolyester is PBT. It is to be understood that such terephthalate-basedpolyesters can include small amounts of isophthalate esters as well.

In order to attain the desired combination of ductility at lowtemperature and chemical resistance, the polyester has a weight averagemolecular weight (Mw) of the polyester ranges from 20,000 to 80,000daltons g/mol, against polystyrene standards, as measured by gelpermeation chromatography in chloroform/hexafluoroisopropanol (5:95,volume/volume ratio) at 25° C. The use of relatively lower molecularweight polyesters, or different polyesters, does not necessarily providecompositions with the desired impact properties and/or chemicalresistance. The polyester has a carboxylic acid end group content from 5to 50 meq/Kg, and a melting point temperature (Tm) from 200 to 285° C.In some instances, the polyester will have a crystallization temperature(Tc) from 120 to 190° C.

The polyesters can have an intrinsic viscosity (as measured inphenol/tetrachloroethane (60:40, volume/volume ratio) at 25° C.) of 0.2to 2.0 deciliters per gram.

Other polyesters can be present in the thermoplastic composition,provided that such polyesters do not significantly adversely affect thedesired properties of the thermoplastic composition. Such additionalpolyesters include, for example, poly(1,4-cyclohexylenedimethyleneterephthalate) (PCT), poly(1,4-cyclohexylenedimethylenecyclohexane-1,4-dicarboxylate) also known aspoly(cyclohexane-1,4-dimethanol cyclohexane-1,4-dicarboxylate) (PCCD),and poly(1,4-cyclohexylenedimethylene terephthalate-co-isophthalate)(PCTA).

Other polyesters that can be present are copolyesters derived from anaromatic dicarboxylic acid (specifically terephthalic acid and/orisophthalic acid) and a mixture comprising a linear C₂₋₆ aliphatic diol(specifically ethylene glycol and butylene glycol); and a C₆₋₁₂cycloaliphatic diol (specifically 1,4-hexane diol, dimethanol decalin,dimethanol bicyclooctane, 1,4-cyclohexane dimethanol and its cis- andtrans-isomers, 1,10-decane diol, and the like) or a linear poly(C₂₋₆oxyalkylene) diol (specifically, poly(oxyethylene) glycol) andpoly(oxytetramethylene) glycol). The ester units comprising the two ormore types of diols can be present in the polymer chain as individualunits or as blocks of the same type of units. Specific esters of thistype include poly(1,4-cyclohexylene dimethylene co-ethyleneterephthalate) (PCTG) wherein greater than 50 mol % of the ester groupsare derived from 1,4-cyclohexanedimethanol; andpoly(ethylene-co-1,4-cyclohexylenedimethylene terephthalate) whereingreater than 50 mol % of the ester groups are derived from ethylene(PCTG). Also included are thermoplastic poly(ester-ether) (TPEE)copolymers such as poly(ethylene-co-poly(oxytetramethylene)terephthalate. Also contemplated for use herein are any of the abovepolyesters with minor amounts, e.g., from 0.5 to 5 percent by weight, ofunits derived from aliphatic acid and/or aliphatic polyols to formcopolyesters. The aliphatic polyols include glycols, such aspoly(ethylene glycol) or poly(butylene glycol).

While other polyesters can be present in the thermoplastic compositions,it is to be understood that the compositions comprise less than 70weight percent (wt. % or wt %), specifically less than 50 wt. %, morespecifically less than 30 wt. %, even more specifically less than 10 wt.% of a polyester derived from a C₃₋₂₀ dicarboxylic acid or a chemicalequivalent thereof, and an aliphatic diol or a chemical equivalentthereof, wherein the aliphatic diol is 1,3-propylene glycol, neopentylglycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol,cyclohexanediol, 1,4-cyclohexanedimethanol, or a combination of theforegoing diols.

In a specific embodiment, it is desirable to limit the amount of otherpolyesters in the thermoplastic composition, in order to maintain goodductility and chemical resistance. Thus, in this embodiment, the polymercomponent of the composition consists essentially of PET and/or PBT, andless than 35.8 wt. % of a different polyester, specifically less than 20wt. % of a different polyester, and even more specifically less than 10wt. % of a different polyester, based on the total weight of thecomposition. In another specific embodiment, the polymer component ofthe thermoplastic composition consists of PET and/or PBT, and less than35.8 wt. % of a different polyester, specifically less than 20 wt. % ofa different polyester, and even more specifically less than 10 wt. % ofa different polyester. In a preferred embodiment, the only polyester inthe composition is PBT, with 0 to 10 wt. % of a different polyester. Inanother preferred embodiment, the only polyester in the composition isPBT.

The polyesters can be obtained by methods well known to those skilled inthe art, including, for example, interfacial polymerization,melt-process condensation, solution phase condensation, andtransesterification polymerization. Such polyester resins are typicallyobtained by the condensation or ester interchange polymerization of thediacid or diacid chemical equivalent component with the diol or diolchemical equivalent component with the component. The condensationreaction may be facilitated by the use of a catalyst of the type knownin the art, with the choice of catalyst being determined by the natureof the reactants. For example, a dialkyl ester such as dimethylterephthalate can be transesterified with butylene glycol using acidcatalysis, to generate poly(butylene terephthalate).

It is possible to use a branched polyester in which a branching agent,for example, a glycol having three or more hydroxyl groups or atrifunctional or multifunctional carboxylic acid has been incorporated.Furthermore, it is sometime desirable to have various concentrations ofacid and hydroxyl end groups on the polyester, depending on the ultimateend use of the thermoplastic composition. Recycled polyesters and blendsof recycled polyesters with virgin polyesters can also be used. Forexample, the PBT can be made from monomers or derived from PET, e.g., bya recycling process.

The thermoplastic composition further comprises a polyfunctional ormultifunctional epoxy compound that can be either polymeric ornon-polymeric. The term “polyfunctional” or “multifunctional” inconnection with the multifunctional epoxy compound means that at leasttwo reactive epoxy groups are present in each molecule of the material.The polyfunctional epoxy material can contain aromatic and/or aliphaticresidues. Examples include epoxy novolac resins, epoxidized vegetable(e.g., soybean, linseed) oils, tetraphenylethylene epoxide,styrene-acrylic copolymers containing pendant glycidyl groups, glycidylmethacrylate-containing polymers and copolymers, and difunctional epoxycompounds such as3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

Polymeric multifunctional epoxy compounds as used herein includeoligomers. Exemplary polymeric multifunctional epoxy materials includethe reaction products of one or more ethylenically unsaturated compounds(e.g., styrene, ethylene and the like) with an epoxy-containingethylenically unsaturated monomer (e.g., a glycidyl C1-4(alkyl)acrylate, allyl glycidyl ethacrylate, and glycidyl itoconate).

For example, in one embodiment the polymeric multifunctional epoxycompound is a styrene-acrylic copolymer (including an oligomer)containing glycidyl groups incorporated as side chains. Several usefulexamples are described in the International Patent Application WO03/066704 A1, assigned to Johnson Polymer, LLC, which is incorporatedherein by reference in its entirety. These materials are based oncopolymers with styrene and acrylate building blocks that have glycidylgroups incorporated as side chains. A high number of epoxy groups perpolymer chain is desired, at least about 10, for example, or greaterthan about 15, or greater than about 20. These polymeric materialsgenerally have a molecular weight greater than about 3000, preferablygreater than about 4000, and more preferably greater than about 6000.These are commercially available from Johnson Polymer, LLC under theJONCRYL® trade name, preferably the JONCRYL® ADR 4368 material.

Another example of a polymeric multifunctional epoxy compound is thereaction product of an epoxy-functional C₁₋₄(alkyl)acrylic monomer witha non-functional styrenic and/or C₁₋₄(alkyl)acrylate and/or olefinmonomer. In one embodiment the polymeric multifunctional epoxy compoundis the reaction product of an epoxy-functional (meth)acrylic monomer anda non-functional styrenic and/or (meth)acrylate monomer. These polymericmultifunctional epoxy compounds are characterized by relatively lowmolecular weights. In another embodiment, the polymeric multifunctionalepoxy compound is an epoxy-functional styrene (meth)acrylic copolymerproduced from an epoxy functional (meth)acrylic monomer and styrene. Asused herein, the term “(meth)acrylic” includes both acrylic andmethacrylic monomers, and the term “(meth)acrylate includes bothacrylate and methacrylate monomers. Examples of specificepoxy-functional (meth)acrylic monomers include, but are not limited to,those containing 1,2-epoxy groups such as glycidyl acrylate and glycidylmethacrylate.

Suitable C₁₋₄(alkyl)acrylate comonomers include, but are not limited to,acrylate and methacrylate monomers such as methyl acrylate, ethylacrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate,s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-amyl acrylate,i-amyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutylacrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate,methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate,methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butylmethacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amylmethacrylate, n-hexyl methacrylate, i-amyl methacrylate,s-butyl-methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate,methylcyclohexyl methacrylate, cinnamyl methacrylate, crotylmethacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate,2-ethoxyethyl methacrylate, and isobornyl methacrylate. Combinationscomprising at least one of the foregoing comonomers can be used.

Suitable styrenic monomers include, but are not limited to, styrene,alpha-methyl styrene, vinyl toluene, p-methyl styrene, t-butyl styrene,o-chlorostyrene, and mixtures comprising at least one of the foregoing.In certain embodiments, the styrenic monomer is styrene and/oralpha-methyl styrene.

In another embodiment, the multifunctional epoxy compound has twoterminal epoxy functionalities, and optionally additional epoxy (orother) functionalities. The compound can further contain only carbon,hydrogen, and oxygen. Difunctional epoxy compounds, in particular thosecontaining only carbon, hydrogen, and oxygen can have a molecular weightof below about 1000 g/mol, to facilitate blending with the polyesterresin. In one embodiment, the difunctional epoxy compounds have at leastone of the epoxide groups on a cyclohexane ring. Exemplary difunctionalepoxy compounds include, but are not limited to,3,4-epoxycyclohexyl-3,4-epoxycyclohexyl carboxylate,bis(3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene di-epoxide,bisphenol diglycidyl ethers such as bisphenol-A diglycidyl ether,tetrabromobisphenol-A diglycidyl ether, glycidol, diglycidyl adducts ofamines and amides, diglycidyl adducts of carboxylic acids such as thediglycidyl ester of phthalic acid the diglycidyl ester ofhexahydrophthalic acid, and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, butadiene diepoxide, vinylcyclohexene diepoxide,dicyclopentadiene diepoxide, and the like. Especially preferred is3,4-epoxycyclohexyl-3,4 epoxycyclohexylcarboxylate.

The multifunctional epoxy compounds can be made by techniques well knownto those skilled in the art. For example, the corresponding alpha- orbeta-dihydroxy compounds can be dehydrated to produce the epoxidegroups, or the corresponding unsaturated compounds can be epoxidized bytreatment with a peracid, such as peracetic acid, in well-knowntechniques. The compounds are also commercially available.

Other preferred materials with multiple epoxy groups are acrylic and/orpolyolefin copolymers and oligomers containing glycidyl groupsincorporated as side chains. Suitable epoxy-functional materials areavailable from Dow Chemical Company under the trade name D.E.R. 332,D.E.R. 661, and D.E.R. 667; from Resolution Performance Products underthe trade name EPON® Resin 1001F, 1004F, 1005F, 1007F, and 1009F(registered to Shell Oil Corporation); from Shell Oil Corporation underthe trade names EPON® 826, 828, and 871; from Ciba Specialty Chemicalsunder the trade names CY-182 and CY-183; and from Dow Chemical Co. underthe tradename ERL-4221 and ERL-4299. Johnson Polymer Co. is a supplierof an epoxy functionalized material known as ADR4368 and 4300. A furtherexample of a polyfunctional carboxy-reactive material is a co- orterpolymer including units of ethylene and glycidyl methacrylate (GMA),sold by Arkema under the trade name LOTADER®.

The multifunctional epoxy compound can comprise other functionalitiesthat are either reactive or non-reactive under the described processingconditions, including hydroxyl, isocyanate, carbodiimide, orthoester,oxazoline, oxirane, aziridine, anhydride, and the like. Themultifunctional epoxy compound can also comprise reactivesilicon-containing materials, for example epoxy-modified silicone andsilane monomers and polymers. If desired, a catalyst or co-catalystsystem can be used to accelerate the reaction between themultifunctional epoxy material and the polyester.

The multifunctional epoxy compound is added to the thermoplasticcompositions in amounts effective to improve visual and/or measuredphysical properties. In one embodiment, the multifunctional epoxycompound is added to the thermoplastic compositions in an amounteffective to improve the solvent resistance of the composition, inparticular the fuel-resistance of the composition. A person skilled inthe art may determine the optimum type and amount of any givenmultifunctional epoxy compound without undue experimentation, using theguidelines provided herein.

In one embodiment the thermoplastic composition comprises more than zeroto 20 wt % of a multifunctional epoxy compound selected from the groupconsisting of cycloaliphatic diepoxy compounds, copolymers comprisingunits derived from the reaction of an ethylenically unsaturated compoundand glycidyl (meth)acrylate, terpolymers comprising units derived fromthe reaction of two different ethylenically unsaturated compounds andglycidyl (meth)acrylate, styrene-(meth)acrylic copolymers containing aglycidyl groups incorporated as a side chain, and a combination thereof.

In one embodiment the thermoplastic composition comprises, based ontotal weight of the composition, from 1 to 15 wt % of a dicycloaliphaticdiepoxy compound or a terpolymer comprising units derived from thereaction of ethene, a C₁₋₆ alkyl (meth)acrylate, and glycidyl(meth)acrylate. In one embodiment the amount of multifunctional epoxycompound in the thermoplastic composition is about 10 to 320milliequivalents epoxy group per 1.0 kg of the polyester.

The thermoplastic composition further comprises anacrylonitrile-butadiene-styrene impact modifier, herein referred to asABS impact modifiers.

The ABS impact modifier is preferably a graft polymer built up from arubber-like core comprising butadiene on which acrylonitrile styrenecopolymer has been grafted. In some instances, the ABS can be a coreshell structure, wherein the core is a polybutadiene that may contain.The shell can be built up for the greater part from a vinyl aromaticcompound and/or vinyl cyanide. The core and/or the shell(s) oftencomprise multi-functional compounds that may act as a cross-linkingagent and/or as a grafting agent. These polymers are usually prepared inseveral stages. Core shell acrylic rubbers can be of various particlesizes. The preferred range is from 50 to 400 micrometers.

ABS impact modifiers contribute to the impact strength of polymercompositions. The rubbery component has a Tg (glass transitiontemperature) below 0° C., preferably between about −40° to about −80° C.Preferably, the rubber content is at least about 10% by weight, mostpreferably, at least about 50%.

Typical other ABS impact modifiers are the butadiene graft polymers ofthe type available from Chemtura under the trade name BLENDEX®. Theimpact modifier comprises a two stage polymer having a butadiene basedrubbery core, and a second stage polymerized from acrylonitrile andstyrene grafted onto cross-linked butadiene polymer, which are disclosedin U.S. Pat. No. 4,292,233 herein incorporated by reference. Othersuitable impact modifiers may be mixtures comprising graft and coreshell impact modifiers made via emulsion polymerization usingacrylonitrile, styrene and butadiene.

The impact modifier can comprise styrene-acrylonitrile copolymer(hereinafter SAN). SAN copolymers are described in ASTM D4203. Thepreferred SAN composition comprises at least 15, preferably 25 to 28,percent by weight acrylonitrile (AN) with the remainder styrene,para-methyl styrene, or alpha methyl styrene. Another example of SANsuseful herein include those modified by grafting SAN to a rubberysubstrate such as, for example, 1,4-polybutadiene, to produce a rubbergraft polymeric impact modifier. High rubber content (greater than 50%by weight) resin of this type (HRG-ABS) can be especially useful forimpact modification of polyester resins.

Another preferred class of impact modifier is referred to as high rubbergraft ABS modifiers, comprising greater than or equal to about 90% byweight SAN grafted onto polybutadiene, the remainder being free SAN. Insome instances the free, ungrafted, SAN can be from 0 to 5 wt % of theimpact modifier composition. ABS can have butadiene contents between 12%and 85% by weight, more particularly at least 50%, and styrene toacrylonitrile ratios between 90:10 and 60:40. Thermoplastic compositionscan include: about 8% acrylonitrile, 43% butadiene and 49% styrene, ormore specifically about 7% acrylonitrile, 50% butadiene and 43% styrene,by weight. These materials are commercially available under the tradenames BLENDEX® 336 and BLENDEX® 415, and BLENDEX® 338 respectively(Chemtura Corporation). Another preferred thermoplastic composition isabout 7% acrylonitrile, 69% butadiene and 24% styrene and is availablecommercially under the trade name BLENDEX® 338 from ChemturaCorporation. Another example of preferred composition is SG24 rubberfrom Ube Cyclon Limited.

In one embodiment the thermoplastic composition comprises from 10 to 49wt % of an acrylonitrile-butadiene-styrene impact modifier composition,having an average particle size of 50 to 400 micrometers, a gel contentof at least 50 wt %, a polybutadiene content of at least 50 wt % of theimpact modifier composition, and a soluble styrene-acrylonitrilecopolymer content ranging from 0 to 5 wt % of the impact modifiercomposition.

The thermoplastic compositions can further comprise from 0 to 2 wt. % ofa fibrillated fluoropolymer, based on total weight of the composition.Suitable fluoropolymers include particulate fluoropolymers which can beencapsulated and which form a fibril, such as poly(tetrafluoroethylene)(PTFE).

The fluoropolymers are capable of being fibrillated (“fibrillatable”)during mixing, individually or collectively, with the polyester.“Fibrillation” is a term of art that refers to the treatment offluoropolymers to produce, for example, a “node and fibril,” network, orcage-like structure. Suitable fluoropolymers include but are not limitedto homopolymers and copolymers that comprise structural units derivedfrom one or more fluorinated alpha-olefin monomers, that is, analpha-olefin monomer that includes at least one fluorine atom in placeof a hydrogen atom. In one embodiment, the fluoropolymer comprisesstructural units derived from two or more fluorinated alpha-olefin, forexample tetrafluoroethylene, hexafluoroethylene, and the like. Inanother embodiment, the fluoropolymer comprises structural units derivedfrom one or more fluorinated alpha-olefin monomers and one or morenon-fluorinated monoethylenically unsaturated monomers that arecopolymerizable with the fluorinated monomers. Examples of suitablefluorinated monomers include and are not limited toalpha-monoethylenically unsaturated copolymerizable monomers such asethylene, propylene, butene, acrylate monomers (e.g., methylmethacrylate and butyl acrylate), vinyl ethers, (e.g., cyclohexyl vinylether, ethyl vinyl ether, n-butyl vinyl ether, vinyl esters) and thelike. Specific examples of fluoropolymers includepolytetrafluoroethylene, polyhexafluoropropylene, polyvinylidenefluoride, polychlorotrifluoroethylene, ethylene tetrafluoroethylene,fluorinated ethylene-propylene, polyvinyl fluoride, and ethylenechlorotrifluoroethylene. Combinations of the foregoing fluoropolymerscan also be used.

Fluoropolymers are available in a variety of forms, including powders,emulsions, dispersions, agglomerations, and the like. “Dispersion” (alsocalled “emulsion”) fluoropolymers are generally manufactured bydispersion or emulsion, and generally comprise about 25 to 60 weight %fluoropolymer in water, stabilized with a surfactant, wherein thefluoropolymer particles are approximately 0.1 to 0.3 micrometers indiameter. “Fine powder” (or “coagulated dispersion”) fluoropolymers canbe made by coagulation and drying of dispersion-manufacturedfluoropolymers. Fine powder fluoropolymers are generally manufactured tohave a particle size of approximately 400 to 500 micrometers. “Granular”fluoropolymers can be made by a suspension method, and are generallymanufactured in two different particle size ranges, including a medianparticle size of approximately 30 to 40 micrometers, and a high bulkdensity product exhibiting a median particle size of about 400 to 500micrometers. Pellets of fluoropolymer may also be obtained andcryogenically ground to exhibit the desired particle size.

Modulated differential scanning calorimetry (MDSC) methods can be usedfor determining extent of fibrillation of the fluoropolymer in thevarious compositions can be used to monitor the course and degree offibrillation.

In one embodiment, the fluoropolymer is encapsulated by a rigidcopolymer, e.g., a copolymer having a Tg of greater than 10° C. andcomprising units derived from a monovinyl aromatic monomer and unitsderived from a C₃₋₆ monovinylic monomer.

Monovinylaromatic monomers include vinyl naphthalene, vinyl anthracene,and the like, and monomers of formula (2):

wherein each X is independently hydrogen, C₁-C₁₂ alkyl, C₃-C₁₂cycloalkyl, C₆-C₁₂ aryl, C₇-C₁₂ arylalkyl, C₇-C₁₂ alkylaryl, C₁-C₁₂alkoxy, C₃-C₁₂ cycloalkoxy, C₆-C₁₂ aryloxy, chloro, bromo, or hydroxy, cis 0 to 5, and R is hydrogen, C₁-C₅ alkyl, bromo, or chloro. Exemplarymonovinylaromatic monomers that can be used include styrene,3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene,alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene,alpha-bromostyrene, dichlorostyrene, dibromostyrene,tetra-chlorostyrene, and the like, and a combination comprising at leastone of the foregoing compounds.

Monovinylic monomers include unsaturated monomers such as itaconic acid,acrylamide, N-substituted acrylamide or methacrylamide, maleicanhydride, maleimide, N-alkyl-, aryl-, or haloaryl-substitutedmaleimide, glycidyl (meth)acrylates, and monomers of the formula (3):

wherein R is hydrogen, C₁-C₅ alkyl, bromo, or chloro, and X^(c) iscyano, C₁-C₁₂ alkoxycarbonyl, C₁-C₁₂ aryloxycarbonyl, hydroxy carbonyl,or the like. Examples of monomers of formula (3) include acrylonitrile,methacrylonitrile, alpha-chloroacrylonitrile, beta-chloroacrylonitrile,alpha-bromoacrylonitrile, acrylic acid, methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, n-propyl(meth)acrylate, isopropyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,and the like, and a combination comprising at least one of the foregoingmonomers. Monomers such as n-butyl acrylate, ethyl acrylate, and2-ethylhexyl acrylate are commonly used. Combinations of the foregoingmonovinyl monomers and monovinylaromatic monomers can also be used.

In a specific embodiment, the monovinylic aromatic monomer is styrene,alpha-methyl styrene, dibromostyrene, vinyltoluene, vinylxylene,butylstyrene, or methoxystyrene, specifically styrene and themonovinylic monomer is acrylonitrile, methacrylonitrile, methyl(meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, orisopropyl (meth)acrylate, specifically acrylonitrile. A usefulencapsulated fluoropolymer is PTFE encapsulated in styrene-acrylonitrile(SAN), also known as TSAN.

Encapsulated fluoropolymers can be made by polymerizing theencapsulating polymer in the presence of the fluoropolymer, for examplean aqueous dispersion of the fluoropolymer. Alternatively, thefluoropolymer can be pre-blended with a second polymer, such as anaromatic polycarbonate or SAN to form an agglomerated material. Eithermethod can be used to produce an encapsulated fluoropolymer. Therelative ratio of monovinyl aromatic monomer and monovinylic comonomerin the rigid graft phase can vary widely depending on the type offluoropolymer, type of monovinylaromatic monomer(s), type ofcomonomer(s), and the desired properties of the composition. The rigidphase can comprise 10 to 95 wt. % of monovinyl aromatic monomer,specifically about 30 to about 90 wt. %, more specifically 50 to 80 wt.% monovinylaromatic monomer, with the balance of the rigid phase beingcomonomer(s). The SAN can comprise, for example, about 75 wt. % styreneand about 25 wt. % acrylonitrile based on the total weight of thecopolymer. An exemplary TSAN comprises about 50 wt. % PTFE and about 50wt. % SAN, based on the total weight of the encapsulated fluoropolymer.

The fluoropolymer can function as a melt strength enhancer. Other meltstrength enhancers, including polymeric or non-polymeric material, canalso be used. One class of melt strength enhancer includes but is notlimited to semicrystalline materials such as polyethylene terephthalate,poly(cyclohexanedimethylene terephthalate), poly(cyclohexanedimethyleneterephthalate glycol), and poly(ethylene-co-1,4-cyclohexanedimethyleneterephthalate). Another class of such melt strength enhancer includeshigh molecular weight polyacrylates. Examples of melt strength enhancersin this class include and are not limited to poly(methyl methacrylate)(PMMA), poly(methacrylate) (PMA), and poly(hydroxyethyl methacrylate).The fluoropolymer can be used in conjunction with the other meltstrength enhancers. Alternatively, when the fluoropolymer is not used,combinations of different non-fluoropolymer melt strength enhancers canbe used. When present, the non-fluoropolymer melt strength enhancers canbe used in an amount from more than 0 to 40 wt. % (i.e., more than zero,up to and including 40 wt. %), based on the total weight of thethermoplastic composition. In another embodiment, the non-fluoropolymermelt strength enhancers can be used in an amount from 1 to 15% byweight, based on the total weight of the thermoplastic composition.

The fibrillated fluoropolymer is used in amounts, based on the totalweight of the thermoplastic composition, from 0 to 2 wt. %, and moreparticularly from 0.1 to 2.0 wt %, and even more particularly from 0.1to 1.0 wt % of the composition. In one embodiment, the fibrillatedfluoropolymer is a polymer encapsulated fluoropolymer comprisingpoly(tetrafluoroethylene) encapsulated with styrene-acrylonitrile and ispresent in an amount ranging from 0.1 to 1.0 wt. %. The encapsulatedfluoropolymer is PTFE encapsulated in styrene-acrylonitrile (SAN), isalso known as TSAN.

The thermoplastic composition can further comprise a stabilizer selectedfrom the group consisting of thioether esters, hindered phenols,phosphites, phosphonites, phosphoric acid, and a combination thereof.

Exemplary phosphites include tris(2,6-di-tert-butylphenyl)phosphite,tris(nonyl phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite or the like.

Exemplary hindered phenols include alkylated monophenols or polyphenols;alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane,commercially available from Ciba Geigy Chemical Company as IRGANOX®1010; butylated reaction products of para-cresol or dicyclopentadiene;alkylated hydroquinones; hydroxylated thiodiphenyl ethers;alkylidene-bisphenols; benzyl compounds; esters ofbeta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydricor polyhydric alcohols;octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,and esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionicacid with monohydric or polyhydric alcohols.

Exemplary thioether esters include C₄₋₂₀ alkyl esters of thiodipropionicacid, including distearyl thiodipropionate, dilaurylthiodipropionate,and ditridecylthiodipropionate. U.S. Pat. Nos. 5,057,622 and 5,055,606describe examples of thioether esters. Still other thioether esterstabilizers include C₄₋₂₀ alkyl esters of beta-laurylthiopropionic acid,including pentaerythritol tetrakis(beta-lauryl thiopropionate) availablefrom Crompton Corporation under the trade name SEENOX™ 412S, and thelike.

Exemplary phosphonites include tetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene diphosphonite, which is available under the trade nameSANDOSTAB® P-EPQ from Sandoz AG, and sold by Clariant; andtetrakis(2,4-di-tert-butylphenyl) 4,4′-biphenylene diphosphonite.

The stabilizers can be combined to form stabilizer compositions. Anexemplary stabilizer composition comprisestetrakis(2,4-di-tert-butylphenyl) 4,4′-biphenylene diphosphonite andphosphoric acid in a weight ratio of 80:20 to 20:80, specifically 70:30to 30:70 based on the weight of the stabilizer composition. Thestabilizer composition can also consist essentially of, or consist of,tetrakis [methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methaneand pentaerythritol-tetrakis(beta-lauryl thiopropionate), in a weightratio of 30:60 to 70:30, specifically 40:60 to 60:40 based on totalweight of the stabilizer composition.

The stabilizer composition is used in an amount ranging from more than 0to 5 wt %, and more specifically 0.1 to 4.0 wt %, and even morespecifically from 1.0 to 4.0 wt %, based on the total weight of thethermoplastic composition. In one embodiment, the stabilizer compositioncomprises a stabilizer selected from the group consisting of thioetheresters, hindered phenols, phosphites, phosphonites, phosphoric acid, anda combination thereof, wherein at least one of the foregoing stabilizershas a molecular weight of greater than 500 daltons. In other instances,all of the stabilizer s will have molecular weight above 500 daltons. Inone embodiment, the stabilizer composition comprises at least 20 wt % ofthe thioether ester, based on the weight of the stabilizer composition,and at least one additional stabilizer selected from the groupconsisting of hindered phenols, phosphites, phosphonites, phosphoricacid, and a combination thereof. In one embodiment the thioether, esteris a C₄₋₂₀ alkyl ester of thiodipropionic acid. In one embodiment thethioether ester is a C₄₋₂₀ alkyl ester of beta-laurylthiopropionic acid.

In general, the thermoplastic compositions comprise 51 to 90 wt. % ofthe high molecular weight polyester, 10 to 49 wt. % of the impactmodifier, and from more than 0 to 5 wt % of a stabilizer. Within thesegeneral guidelines, the relative amounts of each component of thepolyester composition will depend on the type and properties of thepolyester, the type and properties (e.g., reactivity) of the impactmodifier as well as the desired properties of the polyester composition.

For example, improved properties such as low temperature ductility andchemical resistance can be obtained when the thermoplastic compositionscomprise, based on the total weight of the composition, 51 to 90 wt. %of the above described polyester having a weight average molecularweight from 20,000 to 80,000 daltons (for example, PET and/or PBT),specifically 60 to 80 wt. % of the above described polyester having aweight average molecular weight from 20,000 to 80,000 daltons (forexample, PBT).

Improved properties such as low temperature ductility and chemicalresistance can be obtained when the polyester compositions comprise,based on the total weight of the composition, 10 to 49 wt. % of theimpact modifier (for example, a terpolymer comprising units derived fromacrylonitrile, butadiene, and styrene), specifically 10 to 30 wt. % ofthe impact modifier (for example, a terpolymer comprising units derivedfrom acrylonitrile, butadiene, and styrene).

The polyester composition can further comprise an optional catalyst andco-catalyst to facilitate reaction between the epoxy groups of theimpact modifier and the polyester. If present, the catalyst can be ahydroxide, hydride, amide, carbonate, borate, phosphate, C₂₋₃₆carboxylate, C₂₋₁₈ enolate, or a C₂₋₃₆ dicarboxylate of an alkali metalsuch as sodium, potassium, lithium, or cesium, of an alkaline earthmetal such as calcium, magnesium, or barium, or other metal such as zincor a lanthanum metal; a Lewis catalyst such as a tin or titaniumcompound; a nitrogen-containing compound such as an amine halide or aquaternary ammonium halide (e.g., dodecyltrimethylammonium bromide), orother ammonium salt, including a C₁₋₃₆ tetraalkyl ammonium hydroxide oracetate; a C₁₋₃₆ tetraalkyl phosphonium hydroxide or acetate; or analkali or alkaline earth metal salt of a negatively charged polymer.Mixtures comprising at least one of the foregoing catalysts can be used,for example a combination of a Lewis acid catalyst and one of the otherforegoing catalysts.

Specific exemplary catalysts include but are not limited to alkalineearth metal oxides such as magnesium oxide, calcium oxide, barium oxide,and zinc oxide, tetrabutyl phosphonium acetate, sodium carbonate, sodiumbicarbonate, sodium tetraphenyl borate, dibutyl tin oxide, antimonytrioxide, sodium acetate, calcium acetate, zinc acetate, magnesiumacetate, manganese acetate, lanthanum acetate, sodium benzoate, sodiumstearate, sodium benzoate, sodium caproate, potassium oleate, zincstearate, calcium stearate, magnesium stearate, lanthanumacetylacetonate, sodium polystyrenesulfonate, the alkali or alkalineearth metal salt of a PBT-ionomer, titanium isopropoxide, andtetraammonium hydrogensulfate. Mixtures comprising at least one of theforegoing catalysts can be used.

The polyester compositions can include various additives ordinarilyincorporated into resin compositions of this type, with the proviso thatthe additives are selected so as to not significantly adversely affectthe desired properties of the thermoplastic composition. Exemplaryadditives include other polymers (including other impact modifiers),fillers, antioxidants, thermal stabilizers, light stabilizers,ultraviolet light (UV) absorbing additives, quenchers, plasticizers,lubricants, mold release agents, antistatic agents, visual effectadditives such as dyes, pigments, and light effect additives, flameretardants, anti-drip agents, and radiation stabilizers. Combinations ofadditives can be used. The foregoing additives (except any fillers) aregenerally present in an amount from 0.005 to 20 wt. %, specifically 0.01to 10 wt. %, based on the total weight of the composition.

Other polymers that can be combined with the polyesters includepolycarbonates, polyamides, polyolefins, poly(arylene ether)s,poly(arylene sulfide)s, polyetherimides, silicones, silicone copolymers,C₁₋₆ alkyl (meth)acrylate polymers (such as poly(methyl methacrylate)),and C₁₋₆ alkyl (meth)acrylate copolymers, including other impactmodifiers. Such polymers are generally present in amounts of 0 to 10 wt.% of the total composition.

The composition can contain fillers. Particulate fillers include, forexample, alumina, amorphous silica, anhydrous alumino silicates, mica,wollastonite, barium sulfate, zinc sulfide, clays, talc, and metaloxides such as titanium dioxide, carbon nanotubes, vapor grown carbonnanofibers, tungsten metal, barites, calcium carbonate, milled glass,flaked glass, ground quartz, silica, zeolites, and solid or hollow glassbeads or spheres, and fibrillated tetrafluoroethylene. Reinforcingfillers can also be present. Suitable reinforcing fillers include fiberscomprising glass, ceramic, or carbon, specifically glass that isrelatively soda free, more specifically fibrous glass filamentscomprising lime-alumino-borosilicate glass, which are also known as “E”glass. The fibers can have diameters of 6 to 30 micrometers. The fillerscan be treated with a variety of coupling agents to improve adhesion tothe polymer matrix, for example with amino-, epoxy-, amido- ormercapto-functionalized silanes, as well as with organometallic couplingagents, for example, titanium or zirconium based compounds. Fillers,however, can impair the ductility properties and are used sparingly insome embodiments. In one embodiment, the fillers are present in anamounts from 0, or more than 0 to less than 30 weight percent, based onthe total weight of the composition. In one embodiment the filler ispresent in an amount that is more than 0 to 30 weight percent of thetotal weight of the composition, and is selected from the groupconsisting of glass fibers, glass flakes, glass beads, milled glass,silica, wollastonite, talcs, clay, nanoclays, and a combination thereof.

The physical properties of the thermoplastic composition (or an articlederived from the composition) can be varied, depending on propertiesdesired for the application. In an advantageous embodiment, articlesmolded from the compositions have a combination of good low temperatureimpact properties and chemical resistance, particularly resistance toliquid fuel. Liquid fuel as used herein includes fuels such as gasoline.Also included are fuels that contain at least 10, up to 20, up to 40, upto 60, up to 80, or even up to 90 volume percent of a C₁₋₆ alcohol, inparticular ethanol and/or methanol. A mixture of ethanol and methanol isalso included. In one embodiment, a liquid fuel comprises 10 to 90volume % of regular gasoline and 10 to 90 volume % of a C₁-C₆ alcohol.

In one embodiment the composition has an MVR (melt volume flow rate) of1 to 20 cc/10 min., measured in accordance with ASTM D1238 at 265° C., aflexural modulus of greater than 1300 MPa, measured in accordance withASTM D790, and retains at least 75% of its initial tensile elongation atbreak, as measured by ASTM D638, after exposure to Fuel E85 for 28 dayshours at 70° C.

In one embodiment, a bar having a thickness ranging from 2 to 6 mm andcut from a blow molded article comprising the composition has (1) amulti-axial impact total energy from 40 to 100 Joules at −30° C.,measured in accordance with ASTM D3763, and (2) a ductility of at least80%, measured in accordance with ASTM D3763

In one embodiment, the thermoplastic composition has a heat distortiontemperature at 66 psi (0.45 MPa) of greater than or equal to 75° C.

In one embodiment, an article comprising the composition, in particularan injection molded article, has a ductility in a multi-axial impacttest of greater than 80%, measured with 3.2 mm thick disks at −30° C. inaccordance with ASTM D3763. An article comprising the composition, inparticular an injection molded article, can also have a ductility in amulti-axial impact test of greater than or equal to 50%, measured with3.2 mm thick disks at −40° C. in accordance with ASTM D3763.

In another embodiment, a blow molded article comprising the compositionhas a ductility in a multi-axial impact test of greater than or equal to90%, measured at −30° C. in accordance with ASTM D3763 using a samplethat is 8.9 cm (3.5 inches) square that has been cut out from thearticle. A blow molded article comprising the composition can also havea ductility in a multi-axial impact test of greater than or equal to50%, measured at −40° C. in accordance with ASTM D3763, using a samplethat is 8.9 cm (3.5 inches) square and that has been cut out from thearticle.

The compositions can further be formulated such that both an injectionmolded article and a blow molded article can have the above-describedductilities at −30° C. and/or at −40° C.

The compositions can also be formulated such that a molded articlecomprising the composition has a multi-axial impact total energy ofgreater than or equal to 23 Joules (J) measured with 3.2 mm thick disksat −40° C. in accordance with ASTM D3763. In one embodiment, themulti-axial impact total energy ranges from 40 to 100 Joules at −30° C.in accordance with ASTM D3763.

Resistance to a liquid fuel is most conveniently determined by measuringthe molecular weight of a sample of the polyester composition before andafter exposure to the liquid fuel or a mixture of solventsrepresentative of a liquid fuel. Here, an article molded from thecomposition, for example an ASTM tensile bar of 3.2 mm thickness,retains 50% or more of its initial weight average molecular weight afterexposure to a solvent composition comprising gasoline with a minimumoctane rating of 87 for 500 hours at 70° C. In addition, an articlemolded from the composition, for example, an ASTM tensile bar of 3.2 mmthickness can retain 50% or more of its initial weight average molecularweight after exposure to a solvent composition comprising 85 volume %ethanol and 15 volume % gasoline for 500 hours at 70° C.

In a particularly advantageous embodiment, the fuel permeation of anarticle molded from the composition, e.g., an article having a nominalwall thickness from 1.5 mm to 3.5 mm can be less than or equal to 1.5g/m² per day when the article is exposed to a fuel composition for 24hours at 40° C. after equilibrium is achieved at 40° C. In oneembodiment, the fuel is an alcohol-based gasoline having 10 volume % ormore of the alcohol, specifically ethanol. In still another embodiment,the fuel composition that is compliant with Phase II CaliforniaReformulated Certification fuel (CERT). In one embodiment the articlehas a permeability of more than 0 and less than or equal to 1.5 g/m²-dayto ASTM D 471-98 Fuel C measured after exposure to ASTM D 471-98 Fuel Cvapor for 20 weeks at 40° C. using a disc having a diameter of 22 mm anda thickness of 2 mm.

In a more specific embodiment, the thermoplastic composition comprisesfrom 60 to 80 wt % of the polyester; from 10 to 30 wt % of theacrylonitrile-butadiene-styrene impact modifier composition, from 0.1 to20 wt % of the multifunctional epoxy compound, wherein themultifunctional epoxy compound is selected from the group consisting ofdicycloaliphatic diepoxy compounds or terpolymers comprising unitsderived from the reaction of ethene, a C₁₋₆ alkyl (meth)acrylate, andglycidyl (meth)acrylate; from 0.1 to 2 wt % of the fibrillatedfluoropolymer; and from 0.1 to 4 wt % of the stabilizer composition. Inone embodiment, the stabilizer composition comprises at least 20 wt % ofa C₄₋₂₀ alkyl ester of thiodipropionic acid, based on the weight of thestabilizer composition, and at least one additional stabilizer selectedfrom the group consisting of hindered phenols, phosphites, phosphonites,phosphoric acid, and a combination thereof, and wherein a blow moldedarticle of the composition has a multi-axial impact total energy from 40to 100 Joules at −30° C., measured in accordance with ASTM D3763. In oneembodiment, the polyester is poly(1,4-butylene terephthalate). In oneembodiment, the composition does not contain a polyester selected fromthe group consisting of poly(ethylene terephthalate)s,poly(1,3-propylene terephthalate)s, poly(cyclohexanedimethanolterephthalate)s, poly(cyclohexanedimethyleneterephthalate)-co-poly(ethylene terephthalate)s, and a combinationthereof.

In an even more specific embodiment, a thermoplastic compositioncomprises from 60 to 80 wt % poly(1,4-butylene terephthalate); from 10to 30 wt % of the acrylonitrile-butadiene-styrene impact modifiercomposition; from 0.1 to 20 wt % a terpolymer comprising units derivedfrom the reaction of ethene, a C₁₋₆ alkyl (meth)acrylate, and glycidyl(meth)acrylate; from 0.1 to 2 wt % poly(tetrafluoroethylene)encapsulated with styrene-acrylonitrile; and from 0.1 to 4 wt % of thestabilizer composition. In one embodiment the stabilizer compositioncomprises at least 20 wt % of a C₄₋₂₀ alkyl ester ofbeta-laurylthiopropionic acid, based on the weight of the stabilizercomposition, and at least one additional stabilizer selected from thegroup consisting of hindered phenols, phosphites, phosphonites,phosphoric acid, and a combination thereof, and wherein a blow moldedarticle of the composition has a multi-axial impact total energy from 40to 100 Joules at −30° C., measured in accordance with ASTMD-3763.

The polyester compositions are manufactured by combining the variouscomponents under conditions effective to form reaction products. Forexample, powdered polyester, impact modifier, stabilizer, and/or otheroptional components are first blended, optionally with fillers, in aHENSCHEL-Mixer® high speed mixer. Other low shear processes, includingbut not limited to, drum tumbling, vee blender or hand mixing, can alsoaccomplish this blending. The blend is then fed into the throat of atwin-screw extruder via a hopper. Alternatively, one or more of thecomponents can be incorporated into the composition by feeding directlyinto the extruder at the throat and/or downstream through a sidestuffer.Additives can also be compounded into a masterbatch with a desiredpolymeric resin and fed into the extruder. The extruder is generallyoperated at a temperature higher than that necessary to cause thecomposition to flow. The extrudate is immediately quenched in a waterbatch and pelletized. The pellets, so prepared, when cutting theextrudate can be one-fourth inch long or less as desired. Such pelletscan be used for subsequent molding, shaping, or forming.

The polyester compositions can be formed into shaped articles by avariety of known processes for shaping molten polymers, such shaping,extruding, calendaring, thermoforming, casting, or molding thecompositions. Molding includes injection molding, rotational molding,compression molding, blow molding, and gas assist injection molding.

The compositions are particularly useful for the manufacture of articlesthat are exposed to fuels, e.g., fuel tanks, fuel containers, and othercomponents that are exposed to a fuel such as gasoline. In oneembodiment, such articles are blow molded and retain their advantageouslow temperature ductility, chemical resistance, and low fuel permeation.

Examples of other articles include electrical connectors, enclosures forelectrical equipment, e.g., a battery cover, automotive engine parts,components for electronic devices, lighting sockets and reflectors,electric motor parts, power distribution equipment, communicationequipment, tiles, e.g., decorative floor tiles.

In one embodiment, the blow molded article is a fuel tank wherein afterstorage of ASTM E85 fuel for 28 days at 70° C., the composition retainsat least 75% of its initial tensile elongation at break, as measured byASTM D638. In one embodiment, at least a portion of the article ishollow, and the article has a liquid capacity from 0.47 liter (1 pint)to 18.9 liters (5 gallons). In one embodiment, the blow molded articlehas a minimum wall thickness from 1 to 10 millimeters.

In one embodiment, the injection molded article is a fuel tank is a fueltank, wherein after storage of ASTM E85 fuel for 28 days at 70° C., thecomposition retains at least 75% of its initial tensile elongation atbreak, as measured by ASTM D638.

In one embodiment the thermoplastic composition comprises a stabilizercomposition comprising at least 20 wt % thioether ester, based on theweight of the stabilizer composition, and at least one additionalstabilizer selected from the group consisting of hindered phenols,phosphites, phosphonites, phosphoric acid, and a combination thereof;wherein the thermoplastic composition has a ratio of melt viscosity at ashear rate of 50 s⁻¹ to a melt viscosity at a shear rate of 4000 s⁻¹, of6 to 12 measured at 265° C. in accordance with ASTM D3835; and wherein ablow molded sample of the composition has a multi-axial impact totalenergy ranging from 40 to 100 Joules at −30° C., measured in accordancewith ASTM D3763.

Processes of forming articles comprising the compositions are alsodisclosed. In one embodiment, a process for blow molding a fuel tankcomprises heating a thermoplastic composition in a screw-driven meltprocessing device to a temperature of 230 to 300° C. to form a moltencomposition; pushing the molten composition through an orifice to createan annular tube of the molten thermoplastic composition; closing off anend of the annular tube to form a closed end annular tube; encasing theclosed ended annular tube in a mold; blowing a gas into the closed endedannular tube while the thermoplastic composition is above thecrystallization temperature of the composition, until the closed endedtube assumes the shape of the mold to form a shaped tube; and coolingthe shaped tube to temperature below the crystallization temperature ofthe thermoplastic composition to form the article, wherein thecomposition comprises from 51 to 90 wt % of a polyester having a weightaverage molecular weight from 20,000 to 80,000 daltons, a carboxylicacid end group content from 5 to 50 meq/Kg, and a melting pointtemperature (Tm) from 200 to 285° C., in some instances the polyestercan have a crystallization, or solidification temperature (Tc) from 120to 190° C., wherein the polyester is selected from the group consistingof poly(ethylene terephthalate)s, poly(1,4-butylene terephthalate)s,poly(1,3-propylene terephthalate)s, poly(cyclohexanedimethanolterephthalate)s, poly(cyclohexanedimethyleneterephthalate)-co-poly(ethylene terephthalate)s, and a combinationthereof; from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impactmodifier composition having an average particle size from 50 to 400micrometers, a gel content of at least 50 wt %, and a polybutadienecontent of at least 50 wt % of the impact modifier composition; from 0to 20 wt % of a multifunctional epoxy compound; from 0 to 40 wt % of afiller; from 0 to 2 wt % of a fibrillated fluoropolymer; and from morethan 0 to 5 wt % of a stabilizer composition, wherein the stabilizercomposition comprises at least 20 wt % of the thioether ester, based onthe weight of the stabilizer composition, and at least one additionalstabilizer selected from the group consisting of hindered phenols,phosphites, phosphonites, phosphoric acid, and a combination thereof;wherein at least one of the foregoing stabilizers has a molecular weightof greater than 500 daltons; and wherein a blow molded article of thecomposition has a multi-axial impact total energy from 40 to 100 Joulesat −30° C., measured in accordance with ASTM D3763.

In one embodiment, the above described process further comprises blowinga gas into the closed ended annular tube comprising the compositionuntil the closed ended tube has an outer diameter that is greater thanor equal to 1.3 times the outer diameter of the annular tube.

Advantageously, our invention now provides previously unavailablebenefits. The polyester compositions of our invention, and the articlesmade from them, for instance, exhibit a highly useful combination ofperformance properties, namely improved low temperature ductility, goodchemical resistance, and low permeability. Our compositions can includedifferent combination of components and can provide a wide array ofperformance properties useful in many applications. The compositions,and the articles made from the compositions, can exhibit good ductility,low permeability, and resistance to gasoline and short chain alcohols.These properties are especially useful for the manufacture of articlessuch as fuel tanks and containers for gasoline and are well positionedto address new regulatory standards. Compositions of our inventionperform well when subjected to blow molding processes-processes thathave typically compromised the performance of compositions used ininjection molding processes. In fact, the above-mentioned usefulcombination of properties can be achieved regardless whether or not thecompositions are blow molded or injection molded to form articles,thereby providing effective solutions needed by many manufacturers.

The polyester compositions are further illustrated by the followingnon-limiting examples. The amounts of all components in the Tables beloware provided in percent by weight, based on the total weight of theblend components.

Examples 1-14 Materials

Polybutylene terephthalate (PBT) was VALOX brand from SABIC InnovativePlastics, Mw=36,500. Intrinsic viscosity measured in 60:40 phenol:tetrachloro ethane was 1.2 cc/g. Melting point (Tm) was 222° C.Carboxylic acid (COOH) end groups concentration was 45 milliequivalentsper kilogram PBT (Meq./Kg) resin. R-PET is a PBT resin made from postconsumer recycle PET converted to PBT as described in US PublicationNos. 2007/0203243 and 2007/0208160, and has a weight average molecularweight (Mw)=36,000 and Tm=217° C. It is sold by SABIC InnovativePlastics as VALOX brand iQ PBT. TSAN was a 50/50 wt % blend of afibrillating poly tetra fluoro ethylene (PTFE) co-precipitated withpolystyrene acrylonitrile (SAN), from SABIC Innovative Plastics.

Hindered phenol antioxidant was octadecyl-3-(3,5-di tert butyl-4-hydroxyphenyl) propionate, also know as IRGANOX 1076, from Ciba SpecialtyChemicals, Mw about 531. The phosphite antioxidant was ULTRANOX 626 abis(2,4-di tert butylphenyl) pentaerythritol diphosphite from ChemturaCo., Mw=about 604. UVA was a benzotriazole UV stabilizer, TINUVIN 234,from Ciba Specialty Chemicals, Mw=about 447. The thio ester stabilizerwas a low odor pentaerythritol beta lauryl thiopropionate, SEENOX 412S,from Clariant Co., Mw=about 1160. HYTREL 6356 is a polybutyleneterephthalate polytetrahydrofuran block copolymer (PBT-co-PTHF) sold byDuPont Co., Tm=211° C. Polycarbonate (PC) was LEXAN 100 resin from SABICInnovative Plastics, Mw=about 29,900, Tg=about 150° C.

A set of rubbery butadiene based impact modifiers was used in thepolyester blends. SG24 was a high butadiene content ABS from Ube CyclonLtd. BLENDEX 338 ABS rubber was from SABIC Innovative Plastics. Themethyl methacrylate butadiene styrene (MBS) rubber was EXL3691 from Rohmand Haas Co. The approximate composition, particle size, gel content,ungrafted SAN content and molecular weight are shown in Table 1. Whileboth ABS rubbers, SG24 and BLX338, have high butadiene content, highpercent gel and low free (ungrafted) SAN content, the SG24 has muchnarrower particle size distribution that in some instances, whencombined with a high Mw PBT and the high molecular weight stabilizerpackage described herein, especially with unusually high (greater than 1wt %) levels of a high Mw low odor thio ester, give blow molded articleswith high modulus, superior impact strength and good low temperatureductility.

TABLE 1 average % Rubber particle particle size % gel/ Acrylo- % % % %Free Mw Free Modifier size range insolubles nitrile Styrene ButadieneMMA SAN SAN Blendex 338 310 nm  80-600 nm 93 7 24 69 0 7 98000 SG24 260nm 200-400 nm 87 9 25 66 0 13 62000 MBS EXL3691 175 nm — >75 0 12 75 130 N/aTechniques and ProceduresCompounding Conditions

The ingredients were tumble-blended and then extruded on a compounding27 mm vacuum vented Werner Pfleiderer twin screw extruder with aco-rotating mixing screws. The temperature was set at 520° F. (271° C.)and screw speed at 300 rpm. The output rate on this line is about 50lbs/hr. The extrudate was cooled through a water bath prior topelletizing.

Molding Conditions

Injection molded samples: Test parts were injection molded on a Van Dornmolding machine (80T) with a set temperature of approximately 500° F.(260° C.) using a 30 second cycle time. The pellets were dried for 3-4hours at 170° F. (77° C.) in a forced air-circulating oven prior toinjection molding.

Blow molded samples: The samples were extrusion blow molded on a APVblow molding machine with a accumulator type of processor. The machinehad a 2.5-inch diameter screw which has a Sterlex II Barrier Flightscrew design and with a barrel length/diameter ratio of 24/1. The drivemotor is 50 horsepower. The accumulator design is spiral flow and has acapacity of 2.5 lb of standard LEXAN 100 resin. The die diameter was 2inches and the machine had a clamp force of 30 US tons. The melttemperature of the polymer during blow molding was set at 500° F. (260°C.). During the blow molding process, the extruded molten polymer tubewas expanded into a hollow rectangular staircase shape where thesmallest distance between opposing sides was 2, 4 and 6 inches (5.1,10.2, and 15.2 cm). The part blow molded was a hollow rectangularthree-step tool part 11.5 (29.2 cm) inches high and 6 inches (15.2 cm)wide. The height (rise) of the steps is 3.5, 4 and 4 inches respectively(8.9, 10.2, and 10.2 cm). The inside depth of the three steps was 2, 4and 6 inches (5.1, 10.2, and 15.2 cm). The expansion ratio with regardto width was 3.0 (2 inches to 6 inches (5.1 to 15.2 cm)), with regardsto depth the first step had no expansion, the second step expansionratio was 2.0 (2 to 4 inches (5.1 to 10.2 cm)) the third step, furthestfrom the extruder, has a 3.0 expansion ratio of 2 to 6 inches (5.1 to15.2 cm). Larger expansion ratios are also possible.

A cut out from the extrusion blow-molded part (3.5 inches×3.5 inches,(8.9×8.9 cm)) was taken from the flat side of the middle step formultiaxial impact testing.

Mechanical Property Testing

Multiaxial impact testing (MAI) is based on the ASTM method D3763. Thisprocedure provides information on how a material behaves undermultiaxial deformation conditions. The deformation applied is ahigh-speed puncture. An example of a supplier of this type of testingequipment is DYNATUP. Properties reported include total energy absorbed(TE), which is expressed in Joules (J) and ductility of parts in percent(% D) based on whether the part fractured in a brittle or ductilemanner. A ductile part showed yielding where it was penetrated by thetup, a brittle part split into pieces or had a section punched out thatshowed no yielding. The reported test result is calculated as theaverage of ten test plaques for blow molded parts and five test plaquesfor injection-molded parts.

Flexural modulus was measured on 127×12.7×3.2 mm bars using ASTM methodD 790. Flexural strength is reported at yield. Tensile strength wasmeasured on 3.2 mm tensile bars with a 50 mm/min. crosshead speed usingASTM method D638, tensile strength is reported at yield (Y), percentelongation is reported at break (B).

HDT was measured on 127×3.2 mm bars using ASTM method D648 with a 0.445MPa (66 psi) or 1.82 MPa (264 psi) load. The parts were not annealedbefore testing.

Melting point (Tm) was measured using differential scanning calorimetry(DSC) in a method similar to ASTM D3418. The peak Tm was recorded on thesecond heat, heating rate was 20° C./min.

Melt volume rate (MVR) was measured as per ASTM method D1238 at 265° C.with a 5 Kg load on samples dried for 2 to 3 hrs. at 110° C. A 6 minuteequilibration was used before data was collected. MVR is reported incubic centimeters (cc) of polymer melt/10 minutes. Viscosity vs. shearrate was measured on pellets dried 2 to 3 hrs. at 125° C. using ASTMmethod D3835 using a capillary rheometer. The polymer melt was held at aconstant temperature as the shear rate was varied from 20 to 7000sec.⁻¹. The melt viscosity, measured in Pascal-seconds (Pa-s) wasrecorded at a low shear rate, for example 50 sec.⁻¹ and compared to theviscosity at a high rate of shear, for example 4000 sec.⁻¹. A high ratioindicates, (greater than 7) good shear thinning behavior and high meltstrength. High melt strength is especially important in extrusion blowmolding large parts (greater than 2 kg) so that the molten parison canhold its weight while being expanded into the blow molded article.

Molecular weight was determined by gel permeation chromatography (GPC).A Waters 2695 separation module equipped with a single PL HFIP gel(250×4.6 mm) and a Waters 2487 Dual Wavelength Absorbance Detector(signals observed at 273 nm) were used for GPC analysis. Typically,samples were prepared by dissolving 50 mg of the polymer blends in 50 mLof 5/95 volume % hexafluoro isopropyl alcohol/chloroform solution. Theresults were processed using a millennium 32 Chromatography Manager V4.0 Reported molecular weights are relative to polystyrene standards. Asused herein, “molecular weight” refers to weight average molecularweight (Mw).

Fuel Permeation Testing

This procedure is based on “Fuel Permeation Performance of PolymericMaterials” SAE Technical Paper 2001-01-1999; M. Nulmanl et al.

Material used for Permeation testing: An oven capable of holding 40°C.+/−1° a permeability chamber designed to introduce fuel on the bottomthen allow it to volatilize across the plastic part, ASTM Fuel CE10 aCarbotrap C and Carbosieve S-III trap, nitrogen purge, a dual gas flowregulator with quick disconnects a gas calibration standard, GasChromatograph (GC)/Mass spectrometer (MS) with thermal desorption unit,a gas flow meter and a stopwatch. A 1.6 mm plastic specimen was exposedto ASTM Fuel CE10 vapor on one side and the content of the permeatedvapor measured on the other side of the sample. The exposure isconducted in specially sealed chambers. The permeated gases werecaptured on a thermal desorption trap. The composition of permeatedgases is identified using a thermal desorption unit and a GC/MS system.In terms of actual test procedure, 5 mL of the ASTM Fuel CE10 is placedin the permeation chamber. A polymer disc 22 mm in diameter and 1.6 mmthick is placed between Teflon O-rings. The top of the chamber is thenbolted down. The inlet is connected to a nitrogen purge with a flowsetting between 20 and 30 cc/min. This allows for proper gas turnover.At the given times of interest, the flow is stopped, and a thermaldesorption trap is connected to the outlet of the permeation chamber.Timing and flow are started simultaneously at this time. The trap timevaried based on the barrier properties of the material and/or thesensitivity required. The trap material used is of two types: CarbotrapC used to trap hydrocarbons and not ethanol, while Carbosieve SIII isgood for retaining ethanol but not hydrocarbons. A mixture of the twoallows for the analysis of all target compounds. An Agilent/CDS systemthat has a thermal desorption unit was used to quantify the volatilestrapped as described in the section above. Fuel permeability was testedover 20 days and is reported as total permeation (g/m²-day).

Chemical Resistance Measurements: The chemical resistance of the sampleswas evaluated by immersing the standard parts such as a tensile bar inthe corresponding fuel to be tested. If the resistance against E85 isdetermined, the fuel for the experiment was obtained by mixing 85 volumepercent of ethanol with 15 volume percent of gasoline with a knocking(octane) rating of 87. The samples immersed in the test fuel were loadedinto glassware set up and sealed with a lid that has two open ports toconnect the reflux condenser with water circulation and a thermometerfor measuring the temperature. The constant temperature for theexperiment was obtained by immersing the set up in a silicone oil baththat is heated using a standard lab heater plate with magnetic stirrer.Initial molecular weight was recorded for each sample using GPC. Asample was pulled out after predefined intervals to determine ormolecular weight by GPC. The relative performance of various samples wasdetermined using the retention in molecular weight compared to unexposedsample. Retention of tensile properties on exposure was determined in asimilar manner by exposing molded bars to fuel and testing propertiesafter various periods of exposure.

Examples 1-6

The purpose of these examples was to evaluate the performance ofcompositions containing PBT resin blends with ABS rubbery modifier,antioxidants, an ultra violet screener (UVA) and a PTFE/SAN modifier.

The compositions shown in Table 2 were made and tested in accordance tothe procedures described above. The results of Examples 1-6 aresummarized in Table 2.

TABLE 2 1 2 3 4 5 6 PBT 315 76.8 68.8 67.25 67.7 66.5 61.5 TSAN 0.250.25 0.25 0.25 0.25 0.25 SG24 22 30 30 30 30 35 Thio Ester 0.30 0.300.75 1.00 1.50 1.50 Hindered Phenol 0.20 0.20 0.75 0.4 0.75 0.75Phosphite 0.20 0.20 0.75 0.4 0.75 0.75 UVA 0.25 0.25 0.25 0.25 0.25 0.25Properties of Injection Molded Sample MVR 265° C. cc/10 min 19.2 9.9 6.28.2 11.8 7.0 MAI −40° C. TE J (% D) 62 (100%) 56 (100%) 56 (100%) 64(100%) 49 (100%) 46 (100%) MAI −50° C. TE J (% D) 63 (100%) 62 (100%) 62(100%) 58 (100%) 52 (100%) 48 (100%) MAI −60° C. TE J (% D) 70 (100%) 57(100%) 57 (100%) 64 (100%) 54 (100%) 51 (100%) Flex Str., MPa 61.6 51.650.2 48.4 48.0 44.8 Flex Mod., MPa 1830 1570 1530 1507 1460 1380 T Str(Y), MPa 39.2 31.5 30.4 33.0 32.7 31.2 % Elong (B) 279 208 308 251 296265 HDT, 66 psi ° C. 108 83 80 80 78 87 HDT, 264 psi ° C. 54 52 50 47 5057 Properties of Blow Molded Sample MAI −30° C. TE J (% D) 42 (60%)  46(80%)  50 (100%) 55 (100%) 56 (100%) 52 (100%) MAI −40° C. TE J (% D) 17(0%)  40 (40%)  48 (70%)  56 (100%) 48 (90%)  48 (70%) 

Discussion of Results

Examples 1 to 6 in Table 2 show PBT resin blends with 22 to 35 wt % ABSrubbery modifier SG24, antioxidants, an ultra violet screener (UVA) anda PTFE/SAN modifier. Note that the injection molded samples of all theblends have ductile multiaxial impact (MAI) failure and high totalenergy (>45 J) at −50 and −60° C. The blends also have good rigiditywith a flexural modulus above 1300 MPa. Heat resistance under load, asmeasured by HDT at 66 psi, is above 75° C. for all blends. Note thatunder the more demanding extrusion blow molding conditions only blends3, 4, 5 and 6, with a greater than 0.3 wt % thio ester gave greater than50% ductility at −30 or −40° C. Use of this high molecular weightpentaerythritol thioester, Mw about 1178, not only gave blow moldedarticles with good ductility at low temperature, but even at 1.5 wt %loading (Ex 5-6), had low odor with no objectionable mercaptan or“sulfur” odor observed during melt processing by compounding, injectionmolding or blow molding.

Examples 7-11

The compositions shown in Table 3 containing impact modifier were madeand tested in accordance to the procedures described above. The resultsof Examples 7-11 are summarized below in Table 3.

TABLE 3 7 8 9 10 11 PBT 315 68.8 73.8 67.7 66.5 61.5 TSAN 0.25 0.25 0.250.25 0.25 BLX 338 30 25 30 30 35 Thio Ester 0.30 0.30 1.00 1.50 1.50Hindered Phenol 0.2 0.2 0.4 0.75 0.75 Phosphite 0.2 0.2 0.4 0.75 0.75UVA 0.25 0.25 0.25 0.25 0.25 Properties of Injection Molded Sample MVR265° C. cc/10 min 5.9 13.1 6.9 5.5 15.2 MAI −40° C. TE J (% D) 58 (100%)69 (100%) 63 (100%) 50 (100%) 50 (100%) MAI −50° C. TE J (% D) 57 (100%)63 (100%) 50 (100%) 53 (100%) 48 (100%) MAI −60° C. TE J (% D) 61 (100%)68 (100%) 65 (100%) 55 (100%) 50 (100%) Flex Str., MPa 50.1 56.3 43.746.8 41.3 Flex Mod., MPa 1550 1700 1370 1430 1290 T Str (Y), MPa 32.836.3 31.7 31.1 28.6 % Elong (B) 252 250 270 236 224 HDT 66 psi, ° C. 8899 81 75 75 HDT 264 psi, ° C. 52 53 45 51 51 Properties of Blow MoldedSample MAI −30° C. TE J (% D) 20 (10%)  35 (30%)  50 (100%) 49 (100%) 37(80%)  MAI −40° C. TE J (% D) 14 (0%)  18 (0%)  47 (60%)  47 (90%)  46(60%) 

Discussion of Results

Table 3 shows additional examples (7 to 11) of impact modified PBTblends with 25 to 35 wt % ABS rubbery modifier BLX 338. With low thioester content examples 7 and 8 blow molded samples show poor ductilityand low MAI at −30 and −40° C.

Example 12

The composition shown in Table 4 was made and tested in accordance tothe procedures described above, using VALOX brand iQ-PBT. The results ofExamples 12 are summarized in Table 4.

TABLE 4 12 R-PBT 315 67.7 TSAN 0.25 SG24 30 Thio Ester 1.00 HinderedPhenol 0.4 Phosphite 0.4 UVA 0.25 Properties of Injection Molded SampleMVR 265° C. cc/10 min 12 MAI −40° C. TE J (% D) 60 (100%) MAI −50° C. TEJ (% D) 53 (100%) MAI −60° C. TE J (% D) 43 (60%)  Flex Str., MPa 47.2Flex Mod., MPa 1470 T Str (Y), MPa 33.8 % Elong (B) 390 HDT 66 psi, ° C.82 HDT 264 psi, ° C. 45 Properties of Blow Molded Sample MAI −40° C. TEJ (% D) 50 (70%) 

Discussion of Results

Table 4, example 12 shows a blend of 30 wt % SG24 rubber with a PBTregenerated from post consumer scrap PET, (R-PBT). With a high level ofthe high Mw thio ester example 12 shows good low temperature MAIductility even in blow molded parts. No sulfur odor was observed duringmelt processing.

Example 13

The composition shown in Table 5 was made and tested in accordance tothe procedures described above using PBT/PB-co-PTHF/ABS Blends. Theresults of Example 13 are summarized in Table 5.

TABLE 5 13 PBT 315 46.5 TSAN 0.25 Hytrel 6356 20 SG24 30 Thio Ester 1.50Hindered Phenol 0.75 Phosphite 0.75 UVA 0.25 Properties of InjectionMolded Sample MVR 265° C. cc/10 min 12.9 MAI −40° C. TE J (% D) 45(100%) MAI −50° C. TE J (% D) 48 (100%) MAI −60° C. TE J (% D) 51 (60%) Flex Str., MPa 31.3 Flex Mod., MPa 875 T Str (Y), MPa 22.8 % Elong (B)314 HDT 66 psi, ° C. 78 HDT 264 psi, ° C. 47 Properties of Blow MoldedSample MAI −30° C. TE J (% D) 53 (100%) MAI −40° C. TE J (% D) 48 (100%)

Discussion of Results

Table 5, example 13 shows a blend of 30 wt % SG24 rubber with PBT and aPBT polytetrahydrofuran block copolymer (PBT-co-PTHF), HYTREL 6356. Theblend shows good processability. With a high level (1.5 wt %) of thehigh Mw thioether ester, example 13 shows good low temperature MAIductility even in blow molded parts. No sulfur odor was observed duringmelt processing. Note that while tensile elongation a break is above300% and while flexural modulus is reduced, (below 1300 Mpa), the 66 psiheat distortion temperature is retained above 75° C.

Comparative Viscosity Analysis of Examples 4, 9, and 12

The viscosity performance at high and low shear of compositions ofExamples 4, 9, and 12 was evaluated in accordance to the proceduresdescribed above. Table 6 shows the results.

TABLE 6 Shear Viscosity Shear Ratio of shear (Pa-s) at 50 sec−1Viscosity (Pa-s) at viscosity at Example at 250° C. 4000 sec−1 at 250°C. 50 to 4000 sec−1 4 1714 151 11.4 9 1471 158 9.3 12 1438 137 10.5

Discussion of Results

The results show that high melt strength needed for blow molding largeparts is illustrated in the rheological data of Table 6. Examples 4, 9,and 12 with 30 wt % high butadiene content ABS show good melt strengthas evidenced by a ratio of high shear viscosity (4000 sec.⁻¹) to lowshear viscosity (50 sec.⁻¹) at 250° C. of from 9.3 to 11.5.

Example 14 Comparative

The composition containing a combination of PBT and PC shown in Table 7was made and tested in accordance to the procedures described above. Theresults of Comparative Example 14 are summarized in Table 7.

TABLE 7 14 (Comparative) PBT 315 66.32 PC 100 15 MBS EXL3691 18 ThioEster 0.05 Hindered Phenol 0.08 Mono Sodium Phosphate 0.30 UVA 0.25Properties of Injection Molded Sample MVR 265° C. cc/10 min 17.6 MAI−40° C. TE J (% D) 71 (100%) MAI −50° C. TE J (% D) 70 (100%) MAI −60°C. TE J (% D) 67 (100%) Flex Str., MPa 66.4 Flex Mod., MPa 1860 T Str(Y) MPa 43.5 % Elong (B) 212 HDT 66 psi, ° C. 98 HDT 264 psi, ° C. 54Properties of Blow Molded Sample MAI −40° C. TE J (% D) 4 (0%) 

Comparative Example 14 is an impact modified polycarbonate PBT blend.Table 7 shows the properties of an 18% MBS modified PBT composition with15 wt % polycarbonate (PC). The injection molded parts show goodductility from −40 to −60° C. However, with the low thioester contentblow molded parts gave brittle failure and very low MAI values at −40°C.

Comparative Permeability Analysis of Examples 4, 9, and 14

The permeability of compositions of Examples 4, 9, and 14 was evaluatedin accordance to the procedures described above. Table 8 shows theresults.

TABLE 8 Total Permeation (g/m²-day) Example for 1.6 mm disk (20 weeks) 40.34 9 0.50 14 (Comparative) 1.35

Discussion of Results

The PC-PBT blend (Ex 14) shows relative deficiency in terms of fuelpermeability. Table 8 shows the fuel permeability of a 22×1.6 mm sampleof examples 4 and 9 (PBT-ABS) and example 14 (PC-PBT). Example 14 withonly 15% PC has a much higher ASTM fuel CE10 permeability than thePBT-ABS blend examples 4 and 9. Articles made of the PBT-ABS blend willhave lower loss of fuel making more efficient use of the fuel andreducing atmospheric pollution than the PC blends.

Comparative Fuel Resistance Analysis of Examples 4, 9, and 14

The fuel resistance of compositions of Examples 4, 9, and ComparativeExample 14 to E85 fuel was evaluated in accordance to the proceduresdescribed above. Table 9 shows the results.

TABLE 9 Example 0 Days 7 Days 14 Days 21 Days 28 Days % TensileElongation at Break after Exposure to E85 at 70 C. 4 223 219 220 224 2029 237 204 183 204 180 14  257 168 106 18 15 (Comparative) % RetentionTensile Elongation at Break after Exposure to E85, 70° C. 4 100 98 99100 91 9 100 86 77 86 76 14  100 65 41 7 6 % Retention in PBT Mw afterExposure to E85 at 70° C. 4 100 86 72 75 68 9 100 93 75 75 73 14  100 8685 81 77

Discussion of Results

Table 9 shows the effect of immersion in E85 fuel on PBT-ABS and PC-PBTblends (Ex. 4 and 9). After 21 and 28 days exposure to E85 fuel (85 vol.% ethanol) at 70° C. the PBT-ABS blend shows high retention ofelongation at break whereas the PC-PBT blend (Ex. 14) loses almost allits initial elongation after exposure in the same time period. ThePBT-ABS compositions (Ex. 4 and 9) show that at least 75% of initialtensile elongation at break, as measured by ASTM D638, after exposure toFuel E85 for 15 days at 70° C.

In addition, greater than 70% of the initial PBT molecular weight (Mw)was retained even after 28 day exposure to E85 fuel at 70° C.

While the invention has been illustrated and described in typicalembodiments, it is not intended to be limited to the details shown,since various modifications and substitutions are possible withoutdeparting from the spirit of the present invention. As such,modifications and equivalents of the invention herein disclosed mayoccur to persons skilled in the art using no more than routineexperimentation, and all such modifications and equivalents are believedto be within the spirit and scope of the invention as defined by thefollowing claims.

While the invention has been illustrated and described in typicalembodiments, it is not intended to be limited to the details shown,since various modifications and substitutions are possible withoutdeparting from the spirit of the present invention. As such,modifications and equivalents of the invention herein disclosed mayoccur to persons skilled in the art using no more than routineexperimentation, and all such modifications and equivalents are believedto be within the spirit and scope of the invention as defined by thefollowing claims.

1. A thermoplastic composition comprising, based on the total weight ofthe composition: from 51 to 90 wt % of a polyester having a weightaverage molecular weight from 20,000 to 80,000 daltons, a carboxylicacid end group content from 5 to 50 meq/Kg, and a melting pointtemperature from 200 to 285° C., wherein the polyester is selected fromthe group consisting of poly(ethylene terephthalate)s, poly(1,4-butyleneterephthalate)s, poly(1,3-propylene terephthalate)s,poly(cyclohexanedimethanol terephthalate)s, poly(cyclohexanedimethyleneterephthalate)-co-poly(ethylene terephthalate)s, and a combinationthereof; from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impactmodifier composition, having an average particle size of 50 to 400micrometers, a gel content of at least 50 wt %, a polybutadiene contentof at least 50 wt % of the impact modifier composition, and a solublestyrene-acrylonitrile copolymer content ranging from 0 to 5 wt % of theimpact modifier composition; from 0 to 20 wt % of a multifunctionalepoxy compound; from 0 to 40 wt % of a filler; from 0 to 2 wt % of afibrillated fluoropolymer; and from at least about 0.75 wt. % to 5 wt %of a stabilizer composition comprising at least about 0.75 wt % ofthioester having a molecular weight of greater than 500 daltons, whereinthe stabilizer composition comprises at least 20 wt % thioether ester,based on the weight of the stabilizer composition, and wherein at leastone additional stabilizer is selected from the group consisting ofhindered phenols, phosphites, phosphonites, phosphoric acid, and acombination thereof; wherein an article that is blow molded from thethermoplastic composition has a multi-axial impact total energy rangingfrom 40 to 100 Joules at −30° C., a ductility of more than 90% at −30°C., and a ductility of more than 50% at −40° C., measured in accordancewith ASTM D3763; and wherein the thermoplastic composition: has apermeability of more than 0 and less than or equal to 1.5 g/m²-day toASTM D 471-98 Fuel C, measured after exposure to ASTM D 471-98 Fuel Cvapor for 20 weeks at 40° C., using a disc having a diameter of 22 mmand a thickness of 2 mm; has an MVR of 1 to 20 cc/10 min, measured inaccordance with ASTM D1238 at 265° C.; has a flexural modulus of greaterthan 1300 MPa, measured in accordance with ASTM D790; retains at least75% of its initial tensile elongation at break, as measured by ASTMD638, after exposure to Fuel E85 for 28 days at 70° C.; and has a ratioof melt viscosity at a shear rate of 50 s-1 to a melt viscosity at ashear rate of 4000 s-1 of 6 to 12, measured at 265° C. in accordancewith ASTM D3835.
 2. The thermoplastic composition of claim 1, having aheat distortion temperature at 66 psi (0.45 MPa) of greater than orequal to 75° C.
 3. The composition of claim 1, wherein the amount ofmultifunctional epoxy compound in the polyester composition is about 10to 320 milliequivalents epoxy group per 1.0 kg of the polyester.
 4. Thecomposition of claim 1, comprising from more than zero to 20 wt % of themultifunctional epoxy compound, wherein the multifunctional epoxycompound is selected from the group consisting of cycloaliphatic diepoxycompounds, copolymers comprising units derived from the reaction of anethylenically unsaturated compound and glycidyl (meth)acrylate,terpolymers comprising units derived from the reaction of two differentethylenically unsaturated compounds and glycidyl (meth)acrylate,styrene-(meth)acrylic copolymers containing a glycidyl groupsincorporated as a side chain, and a combination thereof.
 5. Thecomposition of claim 1, comprising from 1 to 15 wt % of adicycloaliphatic diepoxy compound or a terpolymer comprising unitsderived from the reaction of ethene, a C₁₋₆ alkyl (meth)acrylate, andglycidyl (meth)acrylate.
 6. The composition of claim 1, wherein thefiller is present in an amount of more than 0 to 30 weight percent ofthe total weight of the composition, and is selected from the groupconsisting of glass fibers, glass beads, glass flakes, milled glass,silica, wollastonite, talcs, clay, nanoclays, and a combination thereof.7. The composition of claim 1, wherein the fibrillated fluoropolymer isa polymer encapsulated fluoropolymer comprisingpoly(tetrafluoroethylene) encapsulated with styrene-acrylonitrile and ispresent in an amount ranging from 0.1 to 1.0 wt. %.
 8. The compositionof claim 1, wherein the thioether ester is a C₄₋₂₀ alkyl ester ofthiodipropionic acid.
 9. The composition of claim 1, wherein thethioether ester is a C₄₋₂₀ alkyl ester of beta-laurylthiopropionic acid.10. The thermoplastic composition of claim 1, comprising from 60 to 80wt % of the polyester; from 10 to 30 wt % of theacrylonitrile-butadiene-styrene impact modifier composition, from 0.1 to20 wt % of the multifunctional epoxy compound, wherein themultifunctional epoxy compound is selected from the group consisting ofdicycloaliphatic diepoxy compounds or terpolymers comprising unitsderived from the reaction of ethene, a C₁ alkyl (meth)acrylate, andglycidyl (meth)acrylate; from 0.1 to 2 wt % of the fibrillatedfluoropolymer; and from 0.75 wt. % to 4 wt % of the stabilizercomposition.
 11. The thermoplastic composition of claim 10, wherein thestabilizer composition comprises at least 20 wt % of a C₄₋₂₀ alkyl esterof thiodipropionic acid, based on the weight of the stabilizercomposition, and at least one additional stabilizer selected from thegroup consisting of C₄₋₂₀ alkyl ester of beta-laurylthiopropionic acid,hindered phenols, phosphites, phosphonites, phosphoric acid, and acombination thereof.
 12. The thermoplastic composition of claim 1,wherein the polyester is poly(1,4-butylene terephthalate), wherein thethermoplastic composition does not contain a polyester selected from thegroup consisting of poly(ethylene terephthalate)s, poly(1,3-propyleneterephthalate)s, poly(cyclohexanedimethanol terephthalate)s,poly(cyclohexanedimethylene terephthalate)-co-poly(ethyleneterephthalate)s, and a combination thereof, and wherein rubberybutadiene based impact modifiers in the thermoplastic compositionconsists of the acrylonitrile-butadiene-styrene impact modifier.
 13. Thethermoplastic composition of claim 1, comprising from 60 to 80 wt %poly(1,4-butylene terephthalate); from 10 to 30 wt % of theacrylonitrile-butadiene-styrene impact modifier composition, from 0.1 to20 wt % a terpolymer comprising units derived from the reaction ofethene, a C₁ alkyl (meth)acrylate, and glycidyl (meth)acrylate; from 0.1to 2 wt % poly(tetrafluoroethylene) encapsulated withstyrene-acrylonitrile; and from 0.75 wt. % to 4 wt % of the stabilizercomposition.
 14. The thermoplastic composition of claim 13, wherein thestabilizer composition comprises at least 20 wt % of a C₄₋₂₀ alkyl esterof beta-laurylthiopropionic acid, based on the weight of the stabilizercomposition, and at least one additional stabilizer selected from thegroup consisting of hindered phenols, phosphites, phosphonites,phosphoric acid, and a combination thereof.
 15. The composition of claim1, wherein the composition contains less than 5 wt % polycarbonate andan article that is blow molded or injection molded article from thecomposition has a permeability of more than 0 and less than 1.35g/m²-day to ASTM D 471-98 Fuel C, measured after exposure to ASTM D471-98 Fuel C vapor for 20 weeks at 40° C., using a disc having adiameter of 22 mm and a thickness of 2 mm.
 16. An injection moldedarticle comprising the composition of claim
 1. 17. The injection moldedarticle of claim 16, wherein the article is a fuel tank, and whereinafter storage of ASTM E85 fuel for 28 days at 70° C.
 18. A blow moldedarticle comprising the composition of claim
 1. 19. The blow moldedarticle of claim 18, wherein the article is a fuel tank and whereinafter storage of ASTM E85 fuel for 28 days at 70° C.
 20. The blow moldedarticle of claim 18, wherein at least a portion of the article ishollow, and the article has a liquid capacity ranging from 0.47 liter (1pint) to 18.9 liters (5 gallons).
 21. The blow molded article of claim18, wherein the article has a minimum wall thickness ranging from 1 to10 millimeters.
 22. The thermoplastic composition of claim 1, whereinthe composition comprises 0 wt % of a multifunctional epoxy compound ispresent.
 23. A thermoplastic composition comprising, based on the totalweight of the composition: from 51 to 90 wt % of a polyester having aweight average molecular weight from 20,000 to 80,000 daltons, acarboxylic acid end group content from 5 to 50 meq/Kg, and a meltingpoint temperature from 200 to 285° C., wherein the polyester ispoly(1,4-butylene terephthalate), from 10 to 49 wt % of anacrylonitrile-butadiene-styrene impact modifier composition, having anaverage particle size of 50 to 400 micrometers, a gel content of atleast 50 wt %, a polybutadiene content of at least 50 wt % of the impactmodifier composition, and a soluble styrene-acrylonitrile copolymercontent ranging from 0 to 5 wt % of the impact modifier composition;from more than 0 to 20 wt % of a multifunctional epoxy compound; from 0to 40 wt % of a filler; from 0.1 to 1.0 wt. % of a fibrillatedfluoropolymer, the fibrillated fluoropolymer being an encapsulatedfluoropolymer comprising poly(tetrafluoroethylene) encapsulated withstyrene-acrylonitrile; from at least about 0.75 wt % to 5 wt % of astabilizer composition comprising at least about 0.75 wt % of thioesterhaving a molecular weight of greater than 500 daltons; wherein thestabilizer composition comprises at least 20 wt % thioether ester, basedon the weight of the stabilizer composition, and wherein at least oneadditional stabilizer is selected from the group consisting of hinderedphenols, phosphites, phosphonites, phosphoric acid, and a combinationthereof; wherein an article that is blow molded from the thermoplasticcomposition has a multi-axial impact total energy ranging from 40 to 100Joules at −30° C., a ductility of more than 90% at −30° C., and aductility of more than 50% at −40° C., measured in accordance with ASTMD3763; and wherein the composition: has a permeability of more than 0and less than or equal to 1.5 g/m²-day to ASTM D 471-98 Fuel C, measuredafter exposure to ASTM D 471-98 Fuel C vapor for 20 weeks at 40° C.,using a disc having a diameter of 22 mm and a thickness of 2 mm; has anMVR of 1 to 20 cc/10 min, measured in accordance with ASTM D1238 at 265°C.; has a flexural modulus of greater than 1300 MPa, measured inaccordance with ASTM D790; and retains at least 75% of its initialtensile elongation at break, as measured by ASTM D638, after exposure toFuel E85 for 28 days at 70° C.; and has a ratio of melt viscosity at ashear rate of 50 s-1 to a melt viscosity at a shear rate of 4000 s-1 of6 to 12, measured at 265° C. in accordance with ASTM D3835.
 24. Thecomposition of claim 23, wherein the composition does not contain apolyester selected from the group consisting of poly(ethyleneterephthalate)s, poly(1,3-propylene terephthalate)s,poly(cyclohexane-dimethanol terephthalate)s, poly(cyclohexanedimethyleneterephthalate)-co-poly(ethylene terephthalate)s, and combinationsthereof.
 25. A process for blow molding a fuel tank, comprising: heatinga thermoplastic composition in a screw-driven melt processing device toa temperature of 230 to 300° C. to form a molten composition; pushingthe molten composition through an orifice to create an annular tube ofthe molten thermoplastic composition; closing off an end of the annulartube to form a closed end annular tube; encasing the closed endedannular tube in a mold; blowing a gas into the closed ended annular tubewhile the thermoplastic composition is above the crystallizationtemperature of the composition, until the closed ended tube assumes theshape of the mold to form a shaped tube; and cooling the shaped tube totemperature below the crystallization temperature of the thermoplasticcomposition to form the article; wherein the composition comprises from51 to 90 wt % of a polyester having a weight average molecular weightfrom 20,000 to 80,000 daltons, a carboxylic acid end group content from5 to 50 meq/Kg, and a melting point temperature from 200 to 285° C.,wherein the polyesters is selected from the group consisting ofpoly(ethylene terephthalate)s, poly(1,4-butylene terephthalate)s,poly(1,3-propylene terephthalate)s, poly(cyclohexanedimethanolterephthalate)s, poly(cyclohexanedimethyleneterephthalate)-co-poly(ethylene terephthalate)s, and a combinationthereof; from 10 to 49 wt % of an acrylonitrile-butadiene-styrene impactmodifier composition, having an average particle size from 50 to 400micrometers, a gel content of at least 50 wt %, and a polybutadienecontent of at least 50 wt % of the impact modifier composition; from 0to 20 wt % of a multifunctional epoxy compound; from 0 to 40 wt % of afiller; from 0 to 2 wt % of a fibrillated fluoropolymer; and from morethan 0.3 to 5 wt % of a stabilizer composition, wherein the stabilizercomposition comprises at least 20 wt % thioether ester, based on theweight of the stabilizer composition, wherein the thioester is presentin the thermoplastic composition in an amount greater than 0.3 wt %, andwherein the thermoplastic composition comprises at least one additionalstabilizer selected from the group consisting of hindered phenols,phosphites, phosphonites, phosphoric acid, and a combination thereof;wherein at least one of the foregoing stabilizers has a molecular weightof greater than 500 daltons; and wherein a blow molded article of thecomposition has a multi-axial impact total energy from 40 to 100 Joulesat −30° C. and a ductility of more than 50% at −40° C. measured inaccordance with ASTM D3763.
 26. The process of claim 25, furthercomprising blowing a gas into the closed ended annular tube comprisingthe composition until the closed ended tube has an outer diameter thatis greater than or equal to 1.3 times the outer diameter of the annulartube.